Spectrophotometric determination of plutonium in highly radioactive liquid waste of a reprocessing plant

Taguchi, Shigeo ; Surugaya, Naoki ; Sato, Soichi ; Hiyama, Toshiaki

AA spectrophotometric determination of plutonium in highly radioactive liquid waste has been developed for safeguards verification analysis. The method offers reduced sample preparation and analysis time compared to isotope dilution mass spectrometry. It uses neodymium as an internal standard, which allows for determining an index for the authentication of the analytical scheme and the inspection procedure. The relative expanded uncertainty of the repeated analysis of plutonium (n = 5) was found to be 8.9 % (coverage factor k = 2) for a typical highly radioactive liquid waste sample (172 mg/L). The determination limit was calculated to be 6.1 mg/L (ten fold's the standard deviation). This method was validated through comparison experiments with isotope dilution mass spectrometry. The analytical results of plutonium in highly radioactive liquid waste using this method were in good agreement with those obtained using isotope dilution mass spectrometry. It is to be noted that the neodymium standard is intended to be provided by the International Atomic Energy Agency so that an inspector can check the instrument conditions as well as the analytical scheme. The proposed method was successfully applied to independent on-site safeguards analysis at the Tokai Reprocessing Plant.